新疆伊犁盆地南缘侏罗纪沉积构造特征及原型盆地性质

发布时间：2018-03-13 15:18

本文选题：伊犁盆地　切入点：侏罗纪　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：伊犁盆地位于天山造山带中,是在塔里木板块和哈萨克斯坦板块的南北对冲挤压作用下形成的大型内陆山间拗陷盆地。伊犁盆地南缘侏罗系砂体中,赋存砂岩型铀矿,砂体的展布特征直接影响着砂岩型铀矿的发育。对盆地南缘侏罗系的沉积构造及沉积相的展布特征研究将有助于了解砂体的展布。自侏罗纪以来,伊犁盆地经历了多次的挤压构造运动,而侏罗纪原型盆地面貌已经改变,恢复原型盆地面貌有助于更好的了解侏罗系沉积相的展布特征。本文以沉积学和沉积盆地构造分析理论为指导,以野外地质调查为基础,综合运用钻孔岩心资料,结合研究区岩石样品粒度特征及已有地球物理资料的解释分析,对伊犁盆地南缘侏罗纪残留地层的沉积特征和相标志进行研究,划分了盆地南缘构造单元,恢复了伊犁盆地南缘侏罗纪不同时期盆地的原始面貌。伊犁盆地南缘发育中下侏罗统水西沟群八道湾组、三工河组和西山窑组,及中侏罗统头屯河组,而上侏罗统不发育。中下侏罗统以陆相沉积为主,同时还发育陆相的水进沉积。研究区发育冲积扇-三角洲前缘沉积体系以及河流-三角洲沉积体系。八道湾组为一套巨厚层的紫红色砾岩,超覆在下伏三叠系之上,为一套冲积扇沉积;三工河组岩性为灰色厚层砂岩夹泥岩,发育不稳定薄煤层,为三角洲前缘相沉积;西山窑组岩性主要为灰色厚层砂岩夹泥岩,发育多层稳定展布厚煤层,说明此时水体较浅,为辫状河三角洲前缘相和平原相沉积;头屯河组主要岩性为杂色泥岩,反映水体进一步变浅,为辫状河三角洲平原相沉积。早侏罗世八道湾期,察布查尔山隆起,盆地发生南北向断陷,在山前形成多个冲积扇扇体,此时湖盆开始扩张,盆地处于强伸展阶段;早侏罗世三工河期,湖盆范围进一步扩大,研究区为一套三角洲前缘相沉积,盆地处于弱伸展阶段;中侏罗世西山窑期,发育多次短旋回的水退和水进,湖盆水体变浅,区域大面积持续沼泽化,形成厚层砂岩层夹泥岩层和多层厚煤层,研究区为一套辫状河三角洲前缘相和平原相沉积;中侏罗世头屯河期,盆地内部水体逐渐退却,为一套辫状河平原相沉积,盆地整体处于弱抬升阶段。
[Abstract]:The Yili basin, located in the Tianshan orogenic belt, is a large inland intermountain depression basin formed by the north and south hedging of the Tarim plate and the Kazakhstan plate. The sandstone-type uranium deposits are located in the Jurassic sandbodies in the southern margin of the Yili Basin. The distribution characteristics of sand bodies directly affect the development of sandstone-type uranium deposits. The study of sedimentary structures and sedimentary facies of Jurassic in the southern margin of the basin will be helpful to understand the distribution of sandbodies. The Yili basin has undergone many compressional tectonic movements, and the appearance of the Jurassic prototype basin has changed. The restoration of prototype basin features is helpful to better understand the distribution characteristics of Jurassic sedimentary facies. This paper, guided by sedimentology and sedimentary basin structural analysis theory and based on field geological survey, makes comprehensive use of borehole core data. Based on the grain size characteristics of rock samples and the interpretation and analysis of geophysical data, the sedimentary characteristics and facies markers of Jurassic residual strata in the southern margin of the Yili Basin are studied, and the tectonic units in the southern margin of the basin are divided. The primitive features of the basins in different Jurassic periods in the southern margin of the Yili Basin have been restored. The southern margin of the Yili Basin has developed the Badaowan formation, the Sangonghe formation and the Xishanyao formation of the Middle and Lower Jurassic Shuixigou Group, as well as the Toutunhe formation of the Middle Jurassic. The upper Jurassic is not developed. The middle and lower Jurassic is dominated by continental sediments. The alluvial fan delta front sedimentary system and the fluvial delta sedimentary system are also developed in the study area. The Badaowan formation is a set of very thick fuchsia conglomerates overlying the Lower Triassic. The lithology of the Sangonghe formation is composed of grey thick sandstone mudstone, unstable thin coal seam and delta front facies deposit, and the lithology of Xishanyao formation is mainly gray thick sandstone mudstone with multi-layer stable spreading thick coal seam. The main lithology of Toutunhe formation is mixed mudstone, which reflects the further shallowness of the water body, and the deposition of braided river delta plain facies, and the early Jurassic Badaowan period, which indicates that the water body is shallow, the braided river delta front facies and plain facies are deposited, and the main lithology of Toutunhe formation is mixed mudstone. In the uplift of the Chabucharr Mountains, the basin occurred a north-south fault depression and formed several alluvial fan bodies in the front of the mountain. At this time, the lake basin began to expand and the basin was in the stage of strong extension, and in the early Jurassic Sangonghe period, the area of the lake basin was further expanded. The study area is a set of delta front facies sedimentary, the basin is in the weak extension stage, the middle Jurassic Xishan kiln period, developed several short cycles of water retreat and water advance, the lake basin water body becomes shallow, the area continues to swamp in large area. A set of braided river delta front facies and plain facies were formed in the study area, while in the Middle Jurassic Toutunhe period, the internal water body of the basin gradually retreated, and a set of braided river plain facies deposits were formed in the study area. The whole basin is in the stage of weak uplift.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.52;P619.14

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